Tobacco – Smoke separator or treater
Patent
1996-05-28
1997-09-30
Bahr, Jennifer
Tobacco
Smoke separator or treater
131332, A24D 104, A24D 300
Patent
active
056717571
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to paper filters for cigarettes.
Fibre-containing filters for cigarettes are well known. In one known form of construction, the filter body consists of a tow of continuous filaments, commonly cellulose acetate (acetate) filaments, arranged parallel to the long axis of the cigarette. In another known form of construction, the filter body consists of pleated or fluted paper compressed into a cylinder. The paper is subjected to a grooving process to allow it to be so pleated or fluted. Such forms of construction contain a single filter element and may be called "mono" filters. Another known form of construction is the so-called "dual" filter which contains two filter elements, for example a paper filter towards the interior and a tow filter towards the exterior of the cigarette. A further known form of construction is the so-called "triple" filter, which contains three filter elements, for example a paper filter and a tow filter as in the "dual" construction separated by an air gap or by an activated carbon filter.
Paper filters are known to be generally more efficient at removing tar from tobacco smoke than are tow filters. High tar removal efficiency is particularly desirable in view of the trend towards low-tar cigarettes. It is an object of the present invention to provide a cigarette filter tip with high tar removal efficiency. It is a further object of the invention to provide various constructions of cigarette with low tar delivery.
According to the present invention there is provided a cigarette filter characterised in that the body of the filter comprises paper which contains or consists essentially of lyocell fibres. The invention further provides a cigarette which incorporates such a filter.
Lyocell fibres are known materials, and their manufacture is described for example in U.S. Pat. No. 4,246,221. They are available commercially from Courtaulds plc under the Trade Mark "Tencel". They are made by dissolving cellulose in a solvent and extruding the solution so formed through a spinnerette into a coagulating bath which serves to precipitate the cellulose and wash the solvent from the fibre. This process may be called solvent-spinning, and lyocell fibres may also be called solvent-spun cellulose fibres. The cellulose is usually woodpulp. The solvent may be a tertiary amine N-oxide, preferably an aqueous tertiary amine N-oxide, in particular N-methylmorpholine N-oxide. If the solvent is a tertiary amine N-oxide, the coagulating bath is preferably an aqueous bath. The solvent-spinning process is to be distinguished from other known processes for the manufacture of cellulose fibres which rely on the formation and decomposition of a chemical derivative of cellulose, for example the viscose process. Lyocell fibres are readily biodegradable. The lyocell fibre may contain a matt pigment such as titanium dioxide, and may be bleached.
The cigarette filter of the invention has a high filtration efficiency in comparison with known paper filters.
Paper for use in the cigarette filter of the invention may be manufactured using conventional papermaking technology and equipment. The basis weight of the paper used in the filter of the invention may in general be similar to that of the conventional paper used in known paper filters, and may generally be in the range 15 to 150, preferably 20 to 80, grams per square meter. The paper may consist essentially of lyocell fibres, or may contain other types of fibre, for example plant fibres such as woodpulp and/or acetate fibres, in addition to the lyocell fibres. It has surprisingly been found that the paper may include up to about 50 percent by weight woodpulp without significant reduction in tar removal efficiency, although naturally at higher proportions than this the efficiency increasingly tends towards that of conventional woodpulp paper. Paper which comprises at least 25 percent by weight lyocell fibres, particularly in blend with woodpulp fibres, may be preferred. Paper which contains about 50 percent by weight of lyocell fibres and o
REFERENCES:
patent: 4246221 (1981-01-01), McCorsley, III
patent: 4416698 (1983-11-01), McCorsley, III
patent: 5022964 (1991-06-01), Crane et al.
patent: 5509430 (1996-04-01), Berger
Dr. R.J.K. Shepherd, "`Green` Filters," Tobacco Reporter, vol. 120, Aug. 1993, pp. 46-48.
Bahr Jennifer
Courtaulds Fibres (Holdings) Limited
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